Friction couples normally require some form of cooling to control the heat that is generated during engagement. This is especially important when using friction discs. A standard way of cooling is to direct cooling fluid in varied quantities across the disc. There are various cooling systems known today to supply additional cooling fluid flow to clutches or the like during initial engagement and full engagement while others are provided to reduce the cooling fluid flow or totally shut off the fluid flow during disengagement in order to reduce drag forces. Still others provide ways to increase the pressure of the cooling fluid flow during initial engagement but they either maintain the increased pressure or totally shut off the cooling fluid flow at full engagement.
One of the problems associated with these systems is that too much fluid flow is available during full engagement than is needed for cooling thus using extra horsepower unnecessarily. Another problem is that reducing fluid flow during disengagement alters the ability to provide the extra fluid flow needed for cooling during the initial contacting of the numerous discs while still having the ability to reduce the fluid flow to a lower level upon reaching full engagement.
The present invention is directed to overcoming one or more of the problems as set forth above.